A stereospecific synthesis of (R) and (S)-mevalonic acids was accomplished by the exposure of Beta-hydroxy-Beta-methyl dimethyl glutarate to pig liver esterase to yield the corresponding half ester of high optical purity, which upon reduction with LiBH4 afforded (R)-mevalono-lactone. The major antihypertensive principle of Eucommia ulmoides was isolated and characterized as pinoresinol di-Beta-glucoside; it was synthesized using a combination of microbiological-chemical methods. BIBLIOGRAPHIC REFERENCES: F.C. Huang, L.F.H. Lee, R.S.D. Mittal, P.R. Ravikumar, J.A. Chan, C.J. Sih, E. Caspi and C.R. Eck, Preparation of (R) and (S)-Mevalonic Acids, J. Amer. Chem. Soc., 97, 4144(1975). J.B. Heather, R.S.D. Mittal and C.J. Sih, Synthesis of the Witchweed Seed Germination Stimulant (+)-Strigol, J. Amer. Chem. Soc., June 23 (1976).